1. Field of the Invention
This invention relates to computer systems, and more particularly to switches for expanding the connection capabilities of computer systems.
2. Description of the Related Art
Intelligent/Integrated drive electronics (IDE) is an interface technology for mass storage devices (e.g., disk drives) wherein the controller is integrated into the drive. AT attachment (ATA) is disk drive interface standard which implements IDE. As a result, the two terms and their acronyms are often used interchangeably. Several versions of the ATA standard exist, including the basic ATA standard, Fast ATA, ATA-2, Fast ATA-2, ATA-3, and Ultra ATA. As used herein, the term “AT attachment” and the acronym “ATA” refer to all variants of ATA and other interface standards implementing IDE. The basic ATA standard (ANSI X3.221-1994) supports a single 16-bit parallel data channel which may be shared by two separate devices configured as master and slave. A typical modern computer system includes two such ATA controllers, allowing up to four devices with ATA interfaces to be connected to the computer system.
Many different types of ATA storage devices are now available. It is believed that with time more and more computer users will seek the ability to connect more than four ATA storage devices to a computer system via ATA controllers. An existing solution for expanding ATA connectivity of a computer system is to add more ATA controllers to the system (e.g., via expansion cards). However, such added ATA controllers are typically coupled to a single bus of the computer system (e.g., a peripheral component interface or PCI bus). Adding multiple ATA controllers in this manner is typically not only costly, the multiple ATA controllers can also significantly increase communication traffic on the bus to which they are coupled, consequently reducing system performance.
Small computer system interface (SCSI) adapters and devices are readily available, and multiple SCSI storage devices can typically be coupled to a computer system via a single SCSI bus and adapter. However, SCSI components are typically more expensive than similar ATA components, and can be difficult to install. For example, to add SCSI connectivity to a computer system, a SCSI adapter often must be installed in the system (e.g., via an expansion card), and the associated driver software must be installed and configured.
It would thus be desirable to have a switch for expanding the ATA connection capabilities of a computer system. Such a switch would allow multiple, relatively inexpensive ATA devices to be coupled to a computer system which may already include an ATA controller.